Abstract: A buck converter for converting a DC input voltage into a DC output voltage comprises a DC input circuit with a positive input terminal and a negative input terminal, for providing a DC input voltage, a converter circuit for converting a DC input voltage into a DC output voltage, and a DC output circuit with a positive output terminal, a negative output terminal and an output capacitor connected between the positive output terminal and the negative output terminal. The buck converter further comprises a switching device with a first switching terminal connected with the positive input terminal and a second switching terminal connected over a charging diode with the negative input terminal, a charging inductor as well as a frequency-dependent back-flow circuit connecting the positive output terminal with a power supply terminal of the switching device for supporting the power supply of the switching device.

Abstract: An LED driver and a driving method thereof include at least two sub-LED drivers connected in series between two terminals of an AC power source. The at least two sub-LED drivers have a common configuration. Each sub-LED driver includes a switch circuit having a first reference ground, an inductor having a first terminal connected to the first reference ground and a first capacitor. The first capacitor has a first terminal connected to a second terminal of the inductor and a second terminal connected to a second reference ground. A load with at least one LED to be driven is connected between the first terminal and the second terminal of the first capacitor. An inductance value of the inductor is designed such that each sub-driver operates in an open loop mode. The LED driver and the driving method thereof can achieve an output current balance between the respective sub-LED drivers.

Abstract: A buck converter for converting a DC input voltage into a DC output voltage comprises a DC input circuit with a positive input terminal and a negative input terminal, for providing a DC input voltage, a converter circuit for converting a DC input voltage into a DC output voltage, and a DC output circuit with a positive output terminal, a negative output terminal and an output capacitor connected between the positive output terminal and the negative output terminal. The buck converter further comprises a switching device with a first switching terminal connected with the positive input terminal and a second switching terminal connected over a charging diode with the negative input terminal, a charging inductor as well as a frequency-dependent back-flow circuit connecting the positive output terminal with a power supply terminal of the switching device for supporting the power supply of the switching device.

Abstract: An LED driver and a driving method thereof include at least two sub-LED drivers connected in series between two terminals of an AC power source. The at least two sub-LED drivers have a common configuration. Each sub-LED driver includes a switch circuit having a first reference ground, an inductor having a first terminal connected to the first reference ground and a first capacitor. The first capacitor has a first terminal connected to a second terminal of the inductor and a second terminal connected to a second reference ground. A load with at least one LED to be driven is connected between the first terminal and the second terminal of the first capacitor. An inductance value of the inductor is designed such that each sub-driver operates in an open loop mode. The LED driver and the driving method thereof can achieve an output current balance between the respective sub-LED drivers.